Generation of Adamts13^S/S mice with 129/Sv-genetic background. (A) Gene and protein structure of ADAMTS13 in the wild-type (Adamts13^L/L) 129/Sv mice, the Adamts13^S/S mice on 129/Sv genetic background, and the Adamts13^−/− mice on 129/Sv genetic background. An intracisternal A-particle (IAP) insertion into intron 23 creates a pseudo-exon 24 including a premature stop codon. ADAMTS13 with a truncated C-terminus is expressed mainly in Adamts13^S/S mice. S indicates signal peptide; P, propeptide; MP, metalloprotease domain; Dis, disintegrin-like domain; T (numbered 1-8), thrombospondin type 1 motif domain; Cys, cysteine-rich domain; Sp, spacer domain; and CUB, complement components C1r/C1s, urchin epidermal growth factor, and bone morphogenic protein-1 domain. (B) Expression of Adamts13 mRNA in liver. Poly(A)⁺ RNA isolated from liver of indicated mice was probed with a 1.3-kb Adamts13 cDNA corresponding to exons 3 to 13. (C) GST-mVWF73-H assay. Plasma ADAMTS13 activity of indicated mice was measured using a recombinant mouse VWF73 peptide, GST-mVWF73-H. Results from 6 mice for each genotype are shown. Standard reactions using graded amounts of pooled plasma from 10 Adamts13^L/L mice were performed simultaneously. (D) FRETS-VWF73 assay. Plasma ADAMTS13 activity in indicated mice was determined using a fluorogenic human VWF73 peptide, FRETS-VWF73. Data are mean ± SD of 6 mice for each genotype. The average activity measured in Adamts13^L/L mice was arbitrarily defined as 100%.